I'm building a search engine using SignalR to deliver partial responses in real time to the client.
The problem occurs when the first search is not over, and the client modifies the value of the textbox (txtTab) and click the button (btnSearch) again. The results of the two queries are mixed because the server keeps the two concurrent executions.
I need that when the client clicks the search button the previous execution is canceled.
Tried using hub.stop () and hub.disconnect (), but I can not.
Sorry my bad english :)
var busca = $.connection.hubBusca;
busca.client.atualizaResultados = function (arr) {
oTable.fnAddData(arr);
};
$.connection.hub.start().done(function () {
$('#btnSearch').click(function () {
if ($('#txtTab').val() != '') {
busca.server.iniciar($('#txtTab').val());
}
});
});
Thanks!
Luiz Fernando
I would suggest creating an additional server and client method to handle the final search (which happens when #btnSearch is clicked).
Instead of invoking busca.server.iniciar invoke something like busca.server.terminar.
I would also suggest setting some sort of boolean flag before calling busca.server.terminar to disable busca.client.atualizaResultados so no preliminary search results interfere with the final search results.
Then in HubBusca.Terminar you could call Clients.Caller.finalesResultados which would not be disabled unlike Clients.Caller.atualizaResultados.
In this way you can ensure that your final search results which are sent to the finalesResultados method will not be replaced by results sent to the atualizaResultados client method.
Sorry for my bad Spanish method names. I used Google Translate.
Related
So I'm playing with Twilio Studio, and building a sample IVR. I have it doing a web request to an API that looks up the customer based on their phone number. That works, I can get/say their name to them.
I'm having trouble with the next step, I want to do another http request and pass the 'customer_id' that I get in webrequest1 to webrequest2, but it almost looks like all the web requests fire right when the call starts instead of in order/serialized.
It looks sorta like this;
call comes in, make http request to lookup customer (i get their customer_id and name)
split on content, if customer name is present, (it is, it goes down this decision path)
do another http request to "get_open_invoice_count", this request needs the customer_id though and not their phone number.
From looking at the logs it's always got a blank value there, even though in the "Say" step just above I can say their customer_id and name.
I can almost imagine someone is going to say I should go use a function, but for some reason I can't get a simple function to do a (got) get request.
I've tried to copy/paste this into a function and I kind of think this example is incomplete: https://support.twilio.com/hc/en-us/articles/115007737928-Getting-Started-with-Twilio-Functions-Beta-
var got = require('got');
got('https://swapi.co/api/people/?search=r2', {json: true})
.then(function(response) {
console.log(response)
twiml.message(response.body.results[0].url)
callback(null, twiml);
})
.catch(function(error) {
callback(error)
})
If this is the right way to do it, I'd love to see one of these ^ examples that returns json that can be used in the rest of the flow. Am I missing something about the execution model? I'm hoping it executes step by step as people flow through the studio, but I'm wondering if it executes the whole thing at boot?
Maybe another way to ask this question is; If I wanted to have the IVR be like
- If I know who you are, i send you down this path, if I know who you are I want to lookup some account details and say them to you and give you difference choices than if you are a stranger.
---- how do you do this?
You're right -- that code excerpt from the docs is just a portion that demonstrates how you might use the got package.
That same usage in context of the complete Twilio Serverless Function could look something like this:
exports.handler = function(context, event, callback) {
var twiml = new Twilio.twiml.MessagingResponse();
var got = require('got');
got('https://example.com/api/people/?search=r2', { json: true })
.then(function(response) {
console.log(response);
twiml.message(response.body.results[0].url);
callback(null, twiml);
})
.catch(function(error) {
callback(error);
});
};
However, another part of the issue here is that the advice in this documentation is perfectly reasonable for Functions when building an app on the Twilio Runtime, but there are a couple of unsaid caveats when invoking these functions from a Studio Flow context. Here's some relevant docs about that: https://support.twilio.com/hc/en-us/articles/360019580493-Using-Twilio-Functions-to-Enhance-Studio-Voice-Calls-with-Custom-TwiML
This function would be acceptable if you were calling it directly from an inbound number, but when you use the Function widget within a Studio flow to return TwiML, Studio releases control of the call.
If you want to call external logic that returns TwiML from a flow, and want to return to that flow later, you need to use the TwiML Redirect widget (see "Returning control to Studio" for details).
However, you don't have to return TwiML to Studio when calling external logic! It sounds like you want to make an external call to get some information, and then have your Flow direct the call down one path or another, based on that information. When using a Runtime Function, just have the function return an object instead of twiml, and then you can access that object's properties within your flow as liquid variables, like {{widgets.MY_WIDGET_NAME.parsed.PROPERTY_NAME}}. See the docs for the Run Function widget for more info. You would then use a "Split Based On..." widget following the function in your flow to direct the call down the desired branch.
The one other thing to mention here is the Make HTTP Request widget. If your Runtime Function is just wrapping a call to another web service, you might be able to get away with just using the widget to call that service directly. This works best when the service is under your control, since then you can ensure that the returned data is in a format that is usable to the widget.
Is it possible to stop (kill) asynchronous Call?
In my app I have at client side sth like:
Meteor.call('doCalculation', function(err, result) {
//do sth with result
});
'doCalculation' may take long time (this is ok) I dont want user to start new call when he/she has already one running call, I want to allow user to stop current call and submit new one. How correctly do this?
The only idea I have is to communicate between client and server using mongo. In some place in 'doCalculation' function I can observe some mongo document/collection and based on this do sth in the function (e.g. call exception). Do you have any better ideas?
You can use a semaphore for this purpose. When the semaphore is 1, requests are allowed to be sent. When the semaphore is 0, requests are not allowed to be sent. The semaphore should be 1 by default and just before you send the request, you need to set it to 0. When a response is successful, you set the semaphore back to 1.
As about the timeout: You could use a time out using setTimeout after sending the request, like this:
if (semaphore) {
var isTimedOut = false;
var isSuccess = false;
semaphore = 0; //No need to use var keyword, as this should be declared outside of this scope
Meteor.call('doCalculation', function(err, result) {
isSuccess = true;
//do sth with result
});
setTimeout(function() {
if (!isSuccess) {
isTimeout = true;
//do something else, to handle the time out state
}
}, 10000);
}
This is tricky, because you cannot generally set timeouts from the client's point of view. You don't need to, for a bunch of architectural reasons. The most important thing is that if you lose network connectivity or the server crashes (two cases timeouts are designed to manage), the client is aware immediately because it is disconnected. You can use Meteor.status().connected if this happens often.
It sounds like you're running a long calculation on the server. My suggestion is to return a calculationId immediately, and then update a collection with progress, e.g., CalculationProgresses.update(calculationId, {$set: {progress: currentProgress}}) as you calculate. Your UI can then update the progress reactively, in the most convenient way possible.
Note, that when you do run long calculations on the server, you need to occasionally "yield," giving the chance for other work to happen. Node, on which Meteor is based, is tricky for long calculations if you don't master this notion of yielding. In Meteor, you can yield easily by updating a collection (e.g., your progress collection). This will solve lots of problems you're probably experiencing as you write your application.
i think you need a server-side solution for this. if you go with a client-side solution, you don't handle 2 cases:
the user reloads their browser
the user uses 2 browsers
i would create these methods:
isCalculationActive() -- this checks if the user already has a calculation active. on the server, you can either keep that fact in memory or write it to the db. on the client, if this returns false, then you can proceed to call doCalculation(). if true, you can give the user a popup or alert or something to ask if they want to cancel and proceed.
doCalculation() -- this cancels any outstanding calculation by that user and starts a new one.
with these implemented, the user can reload their browser w/o affecting either the running calculation or correct behavior. and if they try a 2nd browser, everything should still work as expected.
if you want to give the user the option to simply stop the job and not start a new one, then you can simply create:
cancelCalculation() -- this cancels any outstanding calculation by that user.
I'm trying to follow the "Use the return value of a Meteor method in a template helper" pattern outlined here, except with collections.
Essentially, I've got something like this going:
(server side)
Meteor.methods({
queryTest: function(selector) {
console.log("In server meteor method...");
return MyCollection.find(selector);
}
});
(client side)
Meteor.call('queryTest', {}, function(error, results) {
console.log("in queryTest client callback...");
queryResult = [];
results.forEach(function(result) {
// massage it into something more useful for display
// and append it to queryResult...
});
Session.set("query-result", queryResult);
});
Template.query_test_template.helpers({
query_test_result: function() {
return Session.get("query-result");
}
});
The problem is, my callback (from Meteor.call) doesn't even get invoked.
If I replace the Method with just 'return "foo"' then the callback does get called. Also, if I add a ".fetch()" to the find, it also displays fine (but is no longer reactive, which breaks everything else).
What gives? Why is the callback not being invoked? I feel like I'm really close and just need the right incantation...
If it at all matters: I was doing all the queries on the client side just fine, but want to experiment with the likes of _ensureIndex and do full text searches, which from what I can tell, are basically only available through server-side method calls (and not in mini-mongo on the client).
EDIT
Ok, so I migrated things publish/subscribe, and overall they're working, but when I try to make it so a session value is the selector, it's not working right. Might be a matter of where I put the "subscribe".
So, I have a publish that takes a parameter "selector" (the intent is to pass in mongo selectors).
On the client, I have subscribe like:
Meteor.subscribe('my-collection-query', Session.get("my-collection-query-filter"));
But it has spotty behaviour. On one article, it recommended putting these on Templates.body.onCreate. That works, but doesn't result in something reactive (i.e. when I change that session value on the console, it doesn't change the displayed value).
So, if I follow the advice on another article, it puts the subscribe right in the relevant helper function of the template that calls on that collection. That works great, but if I have MULTIPLE templates calling into that collection, I have to add the subscribe to every single one of them for it to work.
Neither of these seems like the right thing. I think of "subscribing" as "laying down the pipes and just leaving them there to work", but that may be wrong.
I'll keep reading into the docs. Maybe somewhere, the scope of a subscription is properly explained.
You need to publish your data and subscribe to it in your client.
If you did not remove "autopublish" yet, all what you have will automatically be published. So when you query a collection on client (in a helper method for example), you would get results. This package is useful just for quick development and prototyping, but in a real application it should be removed. You should publish your data according to your app's needs and use cases. (Not all users have to see all data in all use cases)
Is there a way to know when data has been initially fully fetched from the server after running Deps.autorun for the first time?
For example:
Deps.autorun(function () {
var data = ItemsCollection.find().fetch();
console.log(data);
});
Initially my console log will show Object { items=[0] } as the data has not yet been fetched from the server. I can handle this first run.
However, the issue is that the function will be rerun whenever data is received which may not be when the full collection has been loaded. For example, I sometimes received Object { items=[12] } quickly followed by Object { items=[13] } (which isn't due to another client changing data).
So - is there a way to know when a full load has taken place for a certain dependent function and all collections within it?
You need to store the subscription handle somewhere and then use the ready method to determine whether the initial data load has been completed.
So if you subscribe to the collection using:
itemSub = Meteor.subscribe('itemcollections', blah blah...)
You can then surround your find and console.log statements with:
if (itemSub.ready()) { ... }
and they will only be executed once the initial dataset has been received.
Note that there are possible ocassions when the collection handle will return ready marginally before some of the items are received if the collection is large and you are dealing with significant latency, but the problem should be very minor. For more on why and how the ready () method actually works, see this.
Meteor.subscribe returns a handle with a reactive ready method, which is set to true when "an initial, complete snapshot of the record set has been sent" (see http://docs.meteor.com/#publish_ready)
Using this information you can design something simple such as :
var waitList=[Meteor.subscribe("firstSub"),Meteor.subscribe("secondSub"),...];
Deps.autorun(function(){
// http://underscorejs.org/#every
var waitListReady=_.every(waitList,function(handle){
return handle.ready();
});
if(waitListReady){
console.log("Every documents sent in publications is now available.");
}
});
Unless you're prototyping a toy project, this is not a solid design and you probably want to use iron-router (http://atmospherejs.com/package/iron-router) which provides great design patterns to address this kind of problems.
In particular, take a moment and have a look at these 3 videos from the main iron-router contributor :
https://www.eventedmind.com/feed/waiting-on-subscriptions
https://www.eventedmind.com/feed/the-reactive-waitlist-data-structure
https://www.eventedmind.com/feed/using-wait-waiton-and-ready-in-routes
Is there any way to make multiple requests to the callback function in asp.net when using the ICallbackEventHandler? I need the results for each result, however, when I iterate through and call the function, I get the result only for the last call. Any way to make it return a result for each call?
This is what I am passing in via javascript:
function NoPostback() {
$(".spans").each(function(index, item) {
CallServer($(item).attr("myattr"));
});
}
In this, myattr is a custom attribute that holds a value (1..10). What I want returned is something like ('you said: ' + id) to be returned for each of the calls, so that I can go ahead and place them in the appropriate holders.
However, only one item is returned which is the final call made. For instance if there are 4 items, it returns only ('you said: 4').
Any idea on how to have all of them returned?
Thanks in advance.
Most Javascript AJAX frameworks either abort any subsequent requests if one is in progress, or they ignore previous requests and only handle the latest. The AJAX request itself will pass through the browser's XmlHttpRequest object, but the rest of the javascript code is running within the pages thread. Currently, there is no concurrent programming with javascript (however this is slated to change.)